Oscillation generation



March 7, 1939. c. w. HANSELL OSCILLATION GENERATION Original Filed Jan14, 1936 6 Sheets-Sheet l SHAPE AND [EA/67H OF #025 SUCH AS 70 RfDZ/CEEFFECT [To HEATER ELEMENT lNVENTOR C. [MHZ/ 25 BY 7 mrw l/ ATTORNEYMarch 7, 1939. c. w. HANSELL OSCILLATION GENERATION Origifial Filed Jan.14,

1936 6 Sheets-Sheet 2 INVENTOR C. 14 HANSELL Z ATTORNEY March 7, 1939. cw HANSELL 2,149,340

05 C ILLAT ION GENERAT ION Original Filed Jan. 14, 1936 6 Sheets-Sheet 3CONTROL ELECTRODE VOL T4 GE 0/ HER 0F CAT/ 00E IN M/LS.

GOA/7R0! ELfC'TRODE VOLT/16E 0/4/1457 ER 0F C4 THODE /N M/LS.

INVENTOR cm .4 ELL BY 7%? MVM/ ATTORNEY March 7, 1939.

c. w. HANSELL 2,149,340

OSCILLATION GENERATION Original Filed Jan. 14, 1936 6 Sheets-Sheet 4 E6' T4 9 Lamp, 4 (OSCILLATOR z il '21 6 /II Vc-- 'E IL k0 2' HEAT/N6CURRENT g MODULATED 7 49 ourpur MODULA T/ON I NPU T HEAT/N6 I- CURRENT(-1 MODULATION INPUT YAMPl/ F/ERI 20 5-122 AMPLIFIER D ETECTOR AMPLIFIERINVENTOR c. 14 HAN ELL- MVM ATTORNEY March 7, 1939. Q w HANSELL2,149,340

- OSCILLATION GENERATION Original Filed Jan. 14, 1 936 e Sheets-Sheet 5II HEAf/NG c HEAT/Na CURRENT CURREN T LOW POWER FACTOR C. W HAMSELL ATTOR N E Y Patented Mar. 7, 1939 2,149,340

UNITED STATES PATENT OFFICE 2,149,340 OSCIHATION GENERATION Clarence W.Hansel], Port Jefferson, N. E, assignor to Radio Corporation of America,a corporation of Delaware Original application January 14, 1936, SerialNo. 59,054. Divided and this application June 24, 1937, Serial No.150,038

19 Claims. (Cl. 250-36) This invention relates broadly to a new andimproducing useful output from the tube. This latproved thermionic tubeof the cathode ray type ter defect is in general present in nearly allother in a new circuit for generating and multiplying cathode ray typetubesknown and represents one alternating currents of any frequency andis a of the main disadvantages attendant on the use division of myUnited States application #59,054 of such tubes. l

filed January 14, 1936. a An object of the present invention is toprovid A specific object of the parent application is to a new tube ofthe cathode ray type which is less provide a new tube of the typedescribed which is limited as to frequency by the rate of flow of theparticularly adapted to relay, amplify, or freelectron stream from thecathode to the control quency multiply or demodulate or modulate orgrid. 10 convert from one frequency to another modu- Another object ofthe present invention is to lated or unmodulated ultra high frequencycurprovide a new and improved tube of the cathode rents and to performsubstantially all other servray type as described in the precedingparagraph ices for which known thermionic tubes may be in which theelectrodes are arranged in a novel used. In addition, my new tube makespossible manner to obtain the utmost use of the electron II theperformance of other functions for which prestream. In this manner, highefllciencyand high viously known tubes are unsuitable. electron currentare obtained.

An object of the present invention is to provide The novel features ofmy tube and of various new and improved oscillation generating ormulcircuits in which said tube may be utilized have tiplying circuitsfor use with tubes of the type been pointed out with particularity inthe claims described in the parent application when operatappended tothis specification. ing at ultra high frequency and lower frequencies.The nature of my novel tube and the mode of In general, tubes knownheretofore are limited operation of the same and of the circuits conintheir application in various respects. They nected therewith will bebetter understood by the 25 have definite upper frequency limitations atfollowing detailed description and therefrom I! which theinter-electrode capacity in effect prowhen read in connection with thedrawings vides a low reactance shunt across the impedance through whichlike reference characters indicate between the elements therebypreventing the like parts and in which building up of substantialpotential difference Figures 1, 2, 4, and 5 show, for purposes of 3between the cathode and grid or anode and grid. illustration, variousmodifications of my novel 80 Moreover, at ultra high frequency the gridpotentube structure; tial reverses'in a time period less than the timeFigure 3 illustrates by curves the operation of required for theelectrons to travel from the the tubes of my invention; cathode tothe-grid. Consequently, the tube is Figure 6 illustrates a circuitarrangement substantially limited to frequencies, the half wherein thenovel tube of my invention is con- 86 periods of which are greater thanthe time it takes nected in a novel circuit and coupled to a source forthe electrons to travel from the cathode to of oscillations to produceoscillations of increased the control grid. frequency;

Tubes of the cathode ray type have been known Figures '7 to 14illustrate the use of my novel 40 heretofore in the art- Moreover, suchtubes have tube in novel circuits arranged to produce sus- 40 been knownin which steps have been taken to tained oscillations of considerableamplitude and overcome some of the difiiculties mentioned above.substantially constant frequency. See, for example, Hansell UnitedStates Patent- In Figures 7 to 14 inclusive, regenerationis pro-#1,938,331 issued December 5, 1933. In a parduced between the anodecircuit and the acceler- I ticular application the electron stream hasbeen ating electrode circuit. 45 deflected laterally and thereby causedto im- In Figure 12, the frequency of the oscillations pinge to avarying extent on one or more suitably produced is controlled by meansof a resonant, positioned anodes. Thus, the action of the tube low powerfactor line; 4 does not depend on the rate of flow of the elec- Figure15 illustrates diagrammatically the estrons from the cathode to thecontrol grid. Howsential elements of a novel transmitter circuit in- 50-ever, in this latter tube low efficiency in operation eludingoscillation generating and modulating of the cathode resultslfrom thenature of the circuits incorporating the tubes of my invention; cathodeand its arrangement with respect to the while other electrodes. .In suchtubes a rather small Figure 16 shows diagrammatically a novelcirpercentage of the electron emission is used in cuit arrangementwherein a thermionic tube of u end 0! the cathode 2 and an outerperiphery which is relatively widely spaced from the cathode 2. Theintermediate portions of the accelerating and control electrode 4 recedefrom the cathode as shown from the inner periphery to the outerperiphery thereof. The cathode 2 is supplied as shown with heavy heatingcurrent through heavy leads L coaxiallywith the cathode which'may beconnected as shown to a source of cathode heating current. The anode Sislocated coaxially with respect to the heating leads of the cathode andis separated from the electron emitting portion of the cathode by adisk-shaped portion 1 arranged as shown. The anode may be maintained atthe desired direct current potential by connecting the same as shown tothe positive terminal of a source of potential.

The arrangement as shown causes electrons leaving difierent points alongthe cathodeto be accelerated at diiIerent rates by the control electrode4 and to acquire diflerent velocities in their travel from the cathodetoward the anode. Those leaving the end oif the cathode near A acquire ahigher velocity than those leaving the cathode near the point B. Thevelocity which may be imparted to the electrons may decreaseprogressively from the point A to the point B and may decrease atvarious rates as desired by properly 1 shaping the acceleratingelectrode 4.

. Due to the large cathode current, which should be derived from aconstant direct current source. a magnetic field exists around thecathode and its end connections. This magnetic field deflects theelectrons drawn out from the cathode toward the anode, if the cathodecurrent is in the correct direction. Those electrons having highvelocity travel a relatively long path in the magnetic field, whilethose having a low velocity, travel a relatively short path. As a resultwhen the tube is arranged in accordance with my invention, all electronsleaving the cathode at one instant strike the cathode stem I or theanode 6 at substantially the same later instant. Moreover, in thearrangements shown all electrons leaving from difierent points along thecathode between points A and B tend to strike the cathode stem at theright of B, or the anode, at the same instant. In other words, in mynovel tube there is a strong focussing of the electron stream on a ringenclosing the cathode lead, which may be selected at will. The locationoi. the ring on which the electrons are focussed is a function of theintensity of the electron stream, the potential of the anode, and of theenergizing and shaping of the electrodes, and in particular of theaccelerating control electrode 4.

The electron flow has been indicated diagrammatically by the shadedareas in Figure 1. These areas in particular indicate the outside limitsof the electron path in their passage from cathode to anode or fromcathode to the cathode stem. The shaded areas III which come to sharppoints on the anode are intended to show a cross section of the volumeoccupied by moving electrons when the anode current is a maximum. Thiscondition is attained principally by applyin a predetermined potentialbetween 2 and 4. The overlapping shaded areas II which come to sharppoints on the shield I on the cathode stem are intended to show across-section of the volume occupied by moving electrons when the anodecurrent is 'zero. This condition is attained when the potential on 4 ismade less positive relative By varying the potential between theaccelerating control electrode 4 and the cathode 2. the position atwhich the electrons strike the anode or return to the cathode stem ortothe shield I on the cathode stem may be varied. Therefore, the currentflow to the anode may be controlled by simply varying the potentialbetween the control electrode and cathode or by varying the anodepotential or both. It may also be controlled by varying the cathodecurrent in any manner to vary the magnetic field but in the presentapplication I prefer to use variation in electric forces instead. Y I 7By adding annular shields I and I4 to the cathode stem as shown inFigure 1 on' each side of the anode, the electrons may be shielded fromthe electric field oi the charged anode during most of their flying timeand variations in anode potential will have little efiect upon the anodecurrent. This results in a high anode impedance similar to that ofshield grid tubes 01' the type'already known in the art and gives a highamplification constant without requiring fiow of current to the controlelectrode during peaks of anode current. 7

Obviously the electron current may also be made to fall upon the shieldI4 by making the potential of 4 suiliciently positive with respect to 2.By making adjustments for varying the electron current between shield i4and anode I the alter- One chamber includes the input electrodes whichare to be connected to the input circuits, while the other chamberincludes the output electrodes which are to be connected to the outputcircuits. This, of course, increases the stability oi. operation of thetube particularly when it is operated at high frequencies at whichshielding between output and input circuits is desirable. Moreover, inFigure 2 the anode 6 has a U-shapedcross section as shown. This reducesor eliminates fiow of current from anode 8 to electrode I due tosecondary emission from the anode when, in operation the anode potentialmay be negative with respect to electrode 9 during portions of theoperating time.

It should be noted in connection with the arrangements shown in Figures1 and 2 that by adjusting the control electrode potential. above orbelow that required to give maximum anode current we may reverse thepolarity oi the alternating current output with respect to the alter--nating current input potential and current. This feature is notpossessed by ordinary tubes, though need for it is often met with inkeying and signalling circuits. As an example, we may convert fromsingle circuit to pushpull circuit amplificaoutputs in pushpull,provided we have the action reversed in the two tubes.

The principles of my new type vacuum tube' may very well be applied toproviding more efiicient cathodes for all sorts of cathode ray tubes,including those in which the brightness of the spot is modulated inaddition to the spot being moved over a fluorescent screen (kinescopetubes). They may also be applied to television transmitting tubes suchas Dr. Zworykin's Iconoscope".

To obtain some idea as to the correct dimenwhere E=voltage.

I=cathode current in amperes.

D=diameter of anode (in this case efiective diameter of accelerating andcontrol electrode) d=diameter of cathode Substituting in this equationwe get:

:0.0188 I (logic 0.3/d) 2 or better yet use Hulls Equation 2, whichassumes a cathode temperature of 2500 K., then:

E=0.000716 d mils (logic D/d) E=0.000716 d (IOgm 300/11) The values of Efor various assumed values of d become M ils Volts The values have beenplotted in Figure 3 and indicate that a cathode diameter of about 86mils would be required for a control electrode having an effectivediameter of about 0.3 inch.

If we assume D=0.6 inch then the control electrode voltage for variouscathode diameters will be M ils Volts 30 32. 8 40 63. 4 50 104 60 70 21690 354 In this case a cathode diameter of 5'7 mils would be about right.

It is noted that plain tungsten filaments, of the sizes required foroperation of 135 volts on about 2.5 watts.

the control electrode. will require filament currents of the same orderof magnitude as we use in water cooled tubes. l If a tube is arranged inaccordance with my invention and includes a 40 mil filament having anactive length of .5 inch in combinationwith a control electrode of 1incheflective' diameter, we would obtain in the ideal case a peak anodecurrent of .5 ampere and in doing so we would use a direct currentcontrol electrode potential of 90 volts. With 90 volts on the anode wemight obtain a maximum alternating current output of By raising theanode potential we should obtain about 25 watts at 900 volts and 250watts at 9000 volts. The filament power required would be about 100watts. The power and voltage gain obtainable adll be very high in my newtube.

Since very heavy cathode current is objectionable in receiving tubesother means in addition to those shown-in Figure 2 for focussing theelectron stream on the anode or target besides the magnetic field isdesirable. Such a focussing and electron timing scheme has been shown inFigure 4. In this figure the tube comprises a control electrode I andindirectly heated cathode 2 having a radially enlarged shielding portion5 as shown. The cathode 2 and controlelectrode l are separated from theanode by a shield and accelerating. electrode 9. Annular openings areprovided in the shield 9 to permit the electron stream, when properlyfocussed, to reach the anode 6. The anode 6 is, as in Figure 2, U shapedin cross section. This shaping of the anode minimizes the effect ofsecondary emission by reducing the possibility of potential gradientswhere secondary emission is produced by primary electron impacts uponthe anode surface and so preventing the secondary emission produced fromreaching the other electrodes. The diaphragm electrode 9 is preferablycharged to a more positive potential than the accelerating and controlelectrode 4. Preferably the diaphragm 9 is brought outside the glassenvelope of the tube as shown to provide a continuation of the metalpartition between the two shielded compartments in the tube. Thecontinuation of the diaphragm 9 may also serve as the mounting for thetube upon the metallic shield l8, which effectively isolates the inputcircuits from energy feed back from the output circuit.

In the operation of the tube electrons leaving the filament are firstacted on chiefly by an electric field due to the control electrode 5.The force is greatest on electrons leaving the cathode from pointsfarthest from the anode. This is due to the shield on the end of thecathode and the size, shape, spacing and potentials of the otherelectrodes. After the electrons leave the cathode they come more andmore under the influence of the electric field produced by the diaphragmelectrode potential and this bends the electron paths in approximatelythe same way as the magnetic field in the tubes of Figs. 1 and 2. I soarrange, shape and energize the electrodes that all electrons leavingthe cathode arrive at the diaphragm electrode 9 at nearly the sameradial distance from the axis of the tube. Moreover, the electronsleaving the cathode at the same instant arrive at the diaphragm atnearly the same later instant and consequently are concentrated on theanode at the same instant.

The areas l6, enclosed by the dotted lines, in Figure 4 represent theelectron paths for the condition of maximum anode current. For othercontrol electrode potentials than that assumed in distance from the axisof the tube at which the electrons arrive at the diaphragm electrode 9may be varied. Consequently the electrons may be made to strike eitherthe diaphragm 9 or the openings in it accordingly to the electrodepotentials. If they strike the openings they will, of course, land onthe anode and produce an anode current. Consequently, we may control theanode current by varying the control electrode or cathode potential withrespect to the diaphragm, or we may vary both. I prefer to vary only thecontrol electrode potential in most cases.

In Figure 4 I have shown openings in the diaphragm 9 of considerableaxial length so that *here will be little potential gradient insidethese openings. This reduces the forces acting on secondary emissionelectrons and reduces the secondary emission from the diaphragm whichcan arrive at the anode.

Of course, my novel tube is applicable to all classes of signallingincluding transmitting as well as receiving. Where large powers are tobe handled I contemplate cooling one or more of the electrodes of thetube. For example, as shown in Fig. 5 the anode electrode 6 of the tubemay be cooled by a circulating fluid. The cathode I is somewhat similarto the cathode 2 of Figs. 1 and 2. Here, however, the cathode terminatesin a radially expanded portion 5 which is continued axially as shown at5 to form a shield for the cathode 2 and for the accelerating electrode4. This axial portion '5 may also serve as one of the leads L forapplying the heating current to the cathode. The radial portion of theshield has openings therein as shown through which the electrons mayreach the anode 6. The magnetic field from the cathode current deflectsthe electrons as in the tubes of Figs. 1 and 2. The dotted lines in theupper half of Fig. 5 show the condition of maximum anode current whilethose in the lower half show a condition of zero anode current. Anothercondition of zero anode current can be obtained by increasing thepositive control electrode potential to make the electrons strikeoutside the openings in 5.

The tube of Fig. 5 may, of course, normally be used with a fluid cooledoutput circuit inductance or coil of copper tubing through which watermay be circulated to the anode as disclosed in Moser, United StatesPatent #1,857,029 dated May 3, 1932. Seealso Hallborgs United StatesPatent #1,963,131 dated June 19, 1934. Although I have shown an anodemade of metallic tubing with a. cylindrical cross section area it willbe understood that the tube may have other shapes. If the tubing has adisk shape or U shaped cross section such that the electrodes strike theanode in a depressed area as they do in Figures 2 and 4 secondaryemission will be reduced and the effect of that which takes place willbe reduced.

Since to obtain high efiiciency in any of the tubes in the foregoingfigures as an oscillator or class C amplifier, we must drive the anodepotential down almost to zero when anode current flows, we must providefor the condition where the anode potential is below the diaphragmpotential. This requires suppressing the effect of secondary emissionfrom the anode. The anode amaeeo in my tube is so shaped as to give verylow potential gradient where the initial electrons strike. This reducesthe secondary emission current which can flow back from anode todiaphragm. Preferably a carbonized anode, or anode of material selectedto minimize secondary emission, is used.

The tubes of the present invention may be utilized for any purpose forwhich any known types of vacuum tubes can be used and, in addition willperform functions for which other known types of tubes are unsuitable.

When it is desired to relay or amplify alternating current potentials ordirect current impulses of any frequency, with circuits similar to thoseshown in Figure 1, the said impulses may be applied to the leads markedinput, connected to the primary winding of a transformer 30, thesecondary winding of which is coupled as shown between the control andacceleratingeiectrode 4 and the cathode 2. The last named connectionmay, if desired, be by way of a bypassing condenser C. The secondarywinding of the transformer may be tuned to the frequency of theoscillations or impulses to be relayed if desired by a variablecondenser 3| connected as shown. The relayed and amplified oscillationsimpressed on the input electrodes are repeated in the tube in the mannerdescribed hereinbeiore and caused to appear on the anode electrode fromwhich they may be set up in an output circuit including a primarywinding connected as shown between the anode 6 and the cathode 2 by wayof a second by-passing condenser C. This primary winding of transformer32 may be tuned by a variable condenser 33 connected as shown. Theoscillations appearing in this tuned circuit may be impressed on thesecondary winding coupled thereto and transferred from said winding toany utilization circuit by way of the leads marked output.

The anode electrode may be connected as shown to a positive point on asource of direct current potential, the negative terminal of which isconnected to ground and to the cathode. The control electrode andaccelerating electrode 4 may be maintained at the desired potential withrespect to the cathode by connecting electrode 4 to a separate source ofpotential or to the desired point on the first named source. The sourcesof potential may be a battery or a. filter network connected with arectifier.

In the description of the novel circuits in which my novel tubeoperates, which follows, the tube has been shown somewhat schematically.The tube of each of the circuits may be the tube shown in Figures 2, 4,or 5.

In Figure 6 I have shown diagrammatically a frequency multiplying systemwherein the thermionic tube of the present invention having itsaccelerating electrode and cathode 2 connected to a tuned circuit 40coupled to a source of high frequency oscillations O. The anode 6 ofthis tube is connected to tuned circuit 40' which is in turn coupled toan output circuit. A variable capacity VC is connected as shown betweenthe anode electrode 6 and accelerating electrode 4 to produce thenecessary feedback. The anode circuit 40' may be tuned to a harmonic ofthe oscillations 20. The oscillations of increased frequency may besupplied from the circuit 40' to any load circuit, as for example anantenna system TA.

Hera-as in the prior case, the oscillations to be amplified ordemodulated may be shunted around the energizing source by way ofby-passingcondensers C, C and C", connected as shown between the lowpotential ends of the input and output circuits and ground and fromground to the cathode of the tube.

When it is desired to generate oscillations, an arrangement as shown inFigure 7 may be utilized. Here, the filament may be heated from a 4source of heating current through a transformer connected to thefilament by a circuit 8 as shown. A tuned oscillatory circuit 45 may beconnected as shown between the controlling and accelerating electrode 4and the electrical center of the filament heating circuit by way ofground and condenser C. The anode electrode 6 may be connected to aninductance 41 variably coupled to the inductance in the tuned circuit45. When proper potentials are applied to the electrodes 4, 9 and 6,sustained oscillations will be produced in the tube and circuits 45, 41and said oscillations may be supplied to any utilization circuit such asan aerial by way of a coupling condenser 48, connected as shown to theanode 6. High frequency oscillations appearing in the circuit 45 and ininductance 41 and on the shielding electrode 9 may be by-passed aroundthe potential sources by wayv of by-passing condensers C, C andconnected as shown from the low potential ends of the anode acceleratingelectrode and shield electrode circuits to ground.

The oscillator shown in Figure 8 is similar in many respects to theoscillator shown in Figure 7. In the oscillator of Figure 9, however, atuned anode circuit 49 is utilized and is variably coupled to aninductance connected with the controlling and accelerating electrode 4.

In the oscillator of Figure 9, a tuned oscillatory circuit 45 isconnected between the accelerating electrode 4 and the cathode 2 and atuned oscillatory circuit 49 is connected between the anode and thecathode and coupled to the first named circuit, thus inductive feedbackcoupling is provided and oscillations may be produced with eitherpolarity of feedback coupling provided suitable power supply potentialsare applied to the tube.

Figure 10 shows an oscillation generator with a tuned anode circuit 49,tuned accelerating electrode circuit 45, and either capacitive orconductive feedback coupling, depending upon the size of the capacity 52in the feedback circuit. Since the tube may be adjusted for eitherpolarity of output with respect to input, by adjusting the bias on 4,and the tuned circuits 45, 49 may be either exactly tuned or detuned ineither direction from the frequency of oscillation, I may use eitherpolarity of feedback. A switch S in the feedback circuit is'shown forreversing the feedback polarity.

Figure 11 shows an oscillation generatorwith a tuned anode circuit 49and tuned circuit 45 connected with the accelerating electrode 4, havingfeedback through a piezo-electric quartz crystal PC for stabilizing thefrequency. Undesired capacity feedback between the electrodes of thecrystal holder may be neutralized by means of a neutralizing condenserNC connected as shown between the high potential terminal of the crystalPC and a point on the tuned circuit 45. A shield 54 may be interposedbetween the anode and control electrode circuits, as shown, for thepurpose ofreducing the undesired feedback between these circuits. I

Since the tube will operate to generate oscillations with eitherpolarity of output relative to input, I may reverse the connections fromthe crystal and neutralizing condenser where'they tap on the inductancein the accelerating electrode oscillation circuit 45.

The frequency of the oscillations generated by my novel tube andcircuits may be'stabilized as shown in Figure 12, by a low power factorresonant circuit or transmission line 60, points on which may beconnected by way of movable taps GI and 62 to the tuned resonant circuit45 con- .nected with the accelerating electrode 4 and the tuned resonantcircuit 49 connected with the anode electrode 6. In this case, thepolarity of the feedback may be reversed if desired by means of thereversing switch S. The resonant transmission line may be as disclosedin my United States application #692,092 filed October 4, 1933, Patent2,095,980, granted October 19, 1937. When the proper charging potentialsare applied to the electrodes in the tube, oscillations are developed inthe tubes and circuits and energy is transferred from the tuned resonantcircuit 49 to the low power factor circuit or line 60 and from the lineto the tuned resonant circuit 45 to reinforce said oscillations andstabilize the frequency thereof. In a modification, the connections fromthe oscillatory circuits 46 and 49 may be made to the same end of theresonant circuit or transmission line 60. In this case, the line may bemade substantially one-quarter Wave length long or any multiple ofone-quarter wave length long, and then feedback of suii'icient amplitudeand correct phase will only be obtained at the resonant frequency of theline. A resonant low power factor line for feedback and stabilizingpurposes in an oscillatory generator has been disclosed in United Statesapplication #692,092 filed October 4, 1933, Patent 2,095,980, grantedOctober 19, 1937.

In some cases, it may be desired to produce and modulate oscillations bymeans of a single tube. In this case, a circuit arrangement as shown inFigure 13 may be utilized. Here, the controlling and acceleratingelectrode 4 and screening electrode 9 are connected in oscillationproducing circuits including the tuned oscillatory circuit 60. Theoscillations produced are modulated in the anode circuit and suppliedfrom the anode circuit by way of the transformer 62 to any utilizationcircuit. In order to prevent reaction of the anode and output circuit onthe oscillation producing circuits, a neutralizing condenser 68 may beconnected as shown between the anode 0 and a point on the tuned circuit69.

The modification shown in Figure 14 is similar to the oscillationgenerator of Figure 13, except that a piezo-electric quartz crystal PChas been included in the circuit connected with 4. In parallel with thecrystal PC is an impedance 64, which supplies direct current potentialto the electrode 4. The crystal on proper adjustment of potentials andcircuits will stabilize the frequency of the oscillations produced inthe selfoscillation circuit including the electrodes 2, 4, 9, thepiezo-electric crystal PC and the tuned circuit 60. Here, as in themodification of Figure 13, the modulating potentials may be applied byway of a transformer 50 to the anode electrode 6 and the device may beneutralized by a condenser 68. The modulating potentials may be suppliedto any circuit by way of coupling condensers 69 and 10.

In Figure 15, I have tubes of the present invention connected in a noveltransmitting circuit. This transmitting circuit comprises an oscillationgenerator 90 in which the accelerating electrode 4 is regenerativelycoupled by way of a piezo-electric crystal PC to the tuned tankcir cult.92 connected with anode 6 in such a manner; I that sustainedoscillations of a frequency determined by PC are: produced when theelectrodes are energized. The crystal has another electrode connected tothe shielding and acceleratingelemtrode 8. The shielding between theanode electrode and circuit and the accelerating electrode and circuitafiordedby 9 may be supplemented by,

'ascreenS arranged asshown. The electrode 4 may be charged with a.positive potentialby wayof aresistance 93. The oscillationsappearing in,-92 are transferred byway ofa lead 94 to the accelerating electrode 4'of an amplifier stage .96. wherein they are amplifiedand appear in the II tuned tank circuit 98 connected with the anode 6! from which they aresupplied in push-pull relation to the accelerating electrodes 4" oiapair a of power amplifiers or modulators in an amplifying and modulatingstage I00; The modulating anode modulation of the carrier waves. Notehere that the use of my novel tube wherein the 3 acceleratingelectrodeimay: be charged positive permits this electrode to: beconnected directly to the anode of the preceding tube asin stages 90, 86and1I02', I05. The many: advantages flowing from this simplifying of theexciting circuits which permits the anode and accelerating electrodesiof adjacent cascaded stagesto derive their energy from the samesource will be apparent to I :-as afrequencymultiplier. Inthelatter'casathe one skilledin the art.

The stage .96 may operate asan amplifier 'and circuit 98 is tuned at aharmonic of the frequency of the oscillations produced in 90. Themodulated oscillations may be impressed on any utilization circuit fromthe tuned circuit H0 connected with the anodes 9" of the tubes in thestage I 00.

When it is desired to receive transmitted signals of any character, Imay utilize a receiving system as illustrated in Figure 16. This systemmay comprise a receiving aerial IIO coupled to an amplifier II2 which isin turn coupled to an amplifier H4. The output of the amplifier H4 maybe connected to demodulate on detector H6 and the output of saiddetector may be coupled to a low frequency amplifier IIB, the output ofwhich may be coupled to any utilization circuit, as for exampletelephones. In order to control the output of the receiver and maintainthe same relatively constant, irrespective of swings in the amplitude ofthe received wave, I couple the amplifier II 4 to a tuned circuit I20coupled between the accelerating electrode 4 and cathode of a thermionictube. The anode electrode of the thermionic tube is connected as shownby way of a source I22 and a resistance I24 to the cathode of the tube.The resistance I24 may be connected as shown by way of an automaticvolume control line AVC to the accelerating electrode and cathode of oneor more thermionic tubes in the amplifier I I2, to thereby control thegain of said amplifier tube in accordance with the potencuits may beused.

1 means for coupling one to the other,

signal amplitude increases above normal, the gain of the amplifier H4 isreduced and the opposite effect isproduced bya decrease in the receivedsignal amplitude- In practice the location of the source I22 -maybechanged or'other anode cir- I claim:

1. In asystem for producing ihighfrequency oscillations, a thermionictube having an elongated electron emission element which when heatedproduces diifused'emission in a direction awayirom the axisofthe tube,means for heating-said emission element. an accelerating andcontrolelectrode located'adjacent one end of said emission element. anadditionalelectrode mounted adjacent the. other end of said emissionele' merit, an alternating current circuit connected between, said firstnamed accelerating and control electrodeand said emission element,.andan I I alternating I current: circuit connected between saidadditionalelectrode and said emission element, each of said last namedcircuits including I I I 2. A, system as recited in. claim 1 in wmcn'the1 I alternating current circuit connected with the additionalelectrodeofsaid tube-is tuned.

'3. A system as recitedin claim 1 wherein I of said alternating currentcircuits aretuned. n z

4. A system as recitedinclaim 1 wherein both of said. alternatingcurrent circuits are tuned and I wherein the coupling: between saidcircuits ini eludes means for reversing the-sense of coupling.

ing means. 6. In a system 5., Asystem as recitedin claim 1 whereinnsaid"circuitsand coupling: includesfrequency stabilizgated electronemissionelement which when heated producesdiifused emission in a direction Iaway from the axis of the'tube, means for heat ing said emissionelement, an accelerating and control electrode located adjacent one endof said emission element, an additional electrode mounted adjacent theother end of said emission element, an alternating current circuitconnected between said first named accelerating and control electrodeand said emission element, a second alternating current circuitconnected between said additional electrode and said emission elementand means for coupling one of said circuits to the other of saidcircuits, said means comprising a low power factor resonant lineconnected between said circuits whereby the frequency of theoscillations produced is stabilized.

7. In a system for producing high frequency oscillations, a thermionictube having an elongated electron emission -element which when heatedproduces diffused emission in a direction away from the axis of thetube, means for heating said emission element, an accelerating andcontrol electrode located adjacent one end of said emission element, analternating current circuit connected between said accelerating andcontrol circuit. and said emission element, an anode mounted adjacentthe other end of said emission element, said anode being connected to anoutput circuit and an additional shielding and accelerating electrodemounted between said anode and said first named electrode, and means forcoupling said output circuit to said alternating current circuit.

8. In a system for producing high frequency oscillations, a thermionictube having an elongated electron emission element which when heatedproduces diffused emission in a direction away irom the axis of thetube, means for heating'said emission element, a control andaccelerating electrode located adjacent one end of said emissionelement, an anode electrode mounted adjacent the other end of saidemission element, an accelerating and shielding electrode mountedintermediate said anode and said emission element, an alternatingcurrent circuit connected between said first named acceleratingelectrode and said emission element, means for maintaining saidshielding electrode positive relative to said emission element, and analternating current circuit connected between said anode and saidemission element, each of said last named circuits including means forcoupling one to the other.

' 9. A system as recited in claim 8 in which an alternating currentcircuit is also connected between said shielding-electrode and saidemission electrode.- I

10. In a system 'for producing high frequency oscillations; a thermionictube having an elongated electron emission element which when heatedproduces difiused emission in a direction away from the axis of thetube, means for heating said emission element, an accelerating andcontrol electrode located adjacent one end of said emission element, ananode electrode mounted adjacent the other end of said emission element,and an accelerating and. shielding electrode mounted intermediate saidanode and said emission element, an alternating current circuitconnected between said first named accelerating electrode andsaid'emission element, means for maintaining said shielding electrodepositive relative to said emission element, an alternating currentcircuit connected between said anode and said emission element, saidlast mentioned means including a low power factor resonant lineconnected to each of said circuits whereby the frequency of oscillationsproduced is stabilized.

11. A system as recited in claim 8 wherein both of said alternatingcurrent circuits are tuned and wherein the coupling between saidcircuits includes a frequency stabilizing means.

12. In a system for producing high frequency oscillations, a thermionictube having an elongated electron emission element which when heatedproduces difiused emission in a direction away from the axis of the.tube, means for heating said emission element, a control andaccelerating electrode located adjacent one end of said emissionelement, an anode electrode mounted adjacent the other end of saidemission element, and an accelerating and shielding electrode mountedintermediate said anode and said emission element, a tuned circuitconnected between said first named accelerating electrode and saidemission element, said tuned circuit including a tapped inductance,means for maintaining said shielding electrode positive relative to saidemission element, a second tuned circuit connected between said anodeand said emission element and means for coupling said tuned circuits oneto the other including a reactance connected to said second tunedcircuit, a switch connected to said reactance and selectivelyconnectible to the taps on the inductance in said first tuned circuitwhereby the coupling sense between said tuned circuits may be reversed.

13. A system as recited in claim 8 wherein both of said alternatingcurrent circuits are tuned and wherein said coupling is inductive andvariable.

14. In a system for producing high frequency oscillations, a thermionictube having an elongated electron emission element which when heatedproduces diffused emission in a direction away from the axis of thetube, means for heating said emission element, an accelerating andcontrol electrode located adjacent one end of said emission element, anadditional electrode niounted adjacent the other end of said emissionelement, an alternating current circuit connected between said firstnamed accelerating and control electrode and said emission element, asecond alternating current circuit connected between said additionalelectrode and said emission element and means for coupling one of saidcircuits to the other of said circuits, said means including a piezoelectric crystal connected therebetween.

' In a. system for producing high frequency "oscillations, a thermionictube having an elongated electron emission element which when heatedproduces diffused emission in a direction away from the axis of thetube, means for heating said emission element, an accelerating andcontrol electrode located adjacent one end of said emission element, anadditional electrode mounted adjacent the other end of said emissionelement, an alternating current circuit connected between said firstnamed accelerating and control electrode and said emission element, asecond alternating current circuit connected between said additionalelectrode and said emission element and means for coupling one of saidcircuits to the other of said circuits, said means including a piezoelectric crystal connected therebetween and neutralizing means connectedbetween a point on said first mentioned alternating current circuit andthe end of said second circuit remote from said additional electrode.

16. In a system for producing high frequency oscillations, a thermionictube having an elongated electron emission element which when heatedproduces diiiused emission in a directiom away from the axis of thetube, means for heating said emission element, an accelerating andcontrol electrode located adjacent one end of said emission element, anadditional electrode mounted adjacent the other end of said emissioneleand selectively connectible to said taps on the inductance in saidfirst named circuit whereby the coupling sense between said circuits maybe reversed.

17. In a system for producing high frequency oscillations, a thermionictube having an elongated electron emission element which when heatedproduces diffused emission in a direction away from the axis of thetube, means for heating said emission element, an accelerating andcontrol electrode located adjacent one end of said emission element, ananode electrode mounted adjacent the other end of said emission element,and an accelerating and shielding electrode mounted intermediate saidanode and said emission element, an alternating current circuitconnected between said first named accelerating electrode and saidemission element, means for maintaining said shielding electrodepositive relative to said emission element, an alternating currentcircuit connected between said anode and said emission element, each ofsaid last named circuits including means for coupling one to the otherand a shield surrounding said tube in the, plane of said acceleratingand shielding electrode.

18. In a system for producing high frequency oscillations, a thermionictube having an elongated electron emission element which when heatedproduces diffused emission in a direction away from the axis of thetube, means for heating said emission element, an accelerating andcontrol electrode located adjacent the end of said emission element, ananode electrode mounted adjacent the other end of said emission element,and an accelerating and shielding electrode mounted intermediate saidanode and said emission element, an alternating current circuitconnected between said first named accelerating electrode and saidemission element, means for maintaining said shielding electrodepositive relative to said emission element, an alternating currentcircuit connected between said anode and said emission element, each ofsaid last named circuits including means for coupling one to the otherand a shield surrounding said tube in the plane of said accelerating andshielding electrode, said means including a piezoelectric crystalconnected between said circuits whereby the frequency of theoscillations produced is stabilized.

19. In a system for producing high frequency oscillations, a thermionictube having an elongated electron emission element which when heatedproduces difiused emission in a direction away from the axis of thetube, means for heating said emission element, a control andaccelerating electrode located adjacent one end of said emissionelement, an anode electrode mounted adjacent the other end of saidemission element and an accelerating and shielding electrode mountedintermediate said anode and said emission element, an alternatingcurrent circuit connected between said first named acceleratingelectrode and said emission element, said circuit including a tappedinductance, means for maintaining said shielding electrode positiverelative to said emission element, an alternating current circuitconnected between said anode and said emission element and means forcoupling said alternating current circuits together, said meansincluding a low power factor resonant line connected to said secondcircuit and selectively connectible to the taps on the inductance insaid first mentioned circuit whereby the coupling sense between saidcircuits may be reversed.

CLARENCE W. HANSELL. o

